1. Field of the Invention
The present invention relates to a silicon thin film member formed by CVD (chemical vapor deposition).
2. Description of the Related Art
A great interest has recently been taken in an amorphous silicon (a-Si) thin film used as material for elements such as thin film transistors. The a-Si thin film is generally formed on a semiconductor substrate including silicon and the like by means of plasma CVD. The substrate is then damaged by charged particles generated when plasma is produced, and a number of defects may occur in an interface between the substrate and a-Si thin film.
A method of forming an a-Si thin film without changing the initial discharge power density which is set lower than 32 mW/cm.sup.2, is proposed (Preprint of 1991 Spring Applied Physics Meeting, 28P-P-S8, p.753 and 28P-S-4, p.752). However, according to "Extended Abstract of the 22nd (1990 International) Conference on Solid State Device and Materials, 1990, pp 681-684" which shows a method of evaluating an interface in the a-Si thin film proposed by the inventors, it has turned out that a number of defects occur in the interface even when the a-Si thin film is formed by the plasma CVD. These defects adversely affect the characteristics of a device using the a-Si thin film. In particular, the defects may be fatal to a device whose characteristics greatly depend upon the defects, such as a thin film transistor in which an interface between the substrate and a-Si thin film serves as an active layer.